Sutures



March 15, 1960 D. H. S. FORBES SUTURES ET AL Filed June 20, 1957 2 SheetsSheet 1 10 j //J //l March 1960 D. H. s. FORBES ET AL 2,928,395

SUTURES Filed June 20, 1957 2 Sheets-Sheet 2 United States Patent SUTURES Donald Hayworth Stacy Forbes and John Alexander Mathams, Balerno, Midlothian, Scotland, assignors to Ethicon, Inc., New Brunswick, N.J., a corporation of New Jersey Application June 20, 1957, Serial No. 669,401 8 Claims. (Cl. 128-4355) This invention relates to new and improved sutures and needles. Heretofore, eyeless needles have been attached to sutures used in surgery by mechanical clamping of metal parts of the needles to the suture.

This presented a special problem in that skill is required to attach the suture to the metallic needle. Such attachment must be done in the most careful manner and with the best equipment, in other words as perfectly as possible, because protrusions in the needle end are apt to damage tissue through which the needle is pulled. Moreover the needle itself is, of necessity, expensive to produce.

Some needles have been attached by engagement of the suture with a screw thread in the needle hole. This method requires that the person attaching the needle to the suture selects the diameter of both needle and suture with extreme care so as to be able to feed the suture into the needle and at the same time be able to lock the suture end securely with the screw thread.

The principal object of this invention is to provide an improved attachment of sutures to needles.

A particular object of the invention is to provide a suture-needle attachment wherein the surface of the entire needle remains as smooth as it was prior to attachment.

Another object of the invention is to provide an attachment of sutures to needles without swaging or otherwise altering the needle, even though, as will be readily understood needles which are'already drilled, possibly with the addition of an internal screw thread, swaged, or providedwith a shaped channel, may also be employed in this invention.

Still another important object of the invention is to provide suture-needle attachment means providing some variation between the relative dimensions of suture and bodiments of the invention the adhesive itself forms a mechanical bond between the suture and the needle as will be hereinaftermade clear.

.Generally the suture needle incorporates a hole or recess into which the end of the suture and the adhesive are introduced. In some preferred embodiments the recess takes the form of a cylindrical hole drilled in the direction of the longitudinal axis of the needle, and if desired it may be provided with an internal screw thread. The screw thread is however somewhat expensive to form and while in certain cases it. assists the adhesive in securing the end of the suture to the needle, a very se- ICC pletely through the needle end.

The suture consists of any filament or thread like material provided that it is strong and does not exert any deleterious affect on the wound. Examples of suitable materials from which sutures can be made are catgut, nylon, silk, cotton, linen, dermal, and metal. In general the preferred materials are catgut, nylon, and silk which has been braided 'into a fine thread and dyed black. s

The expression adhesive is to be understood to mean any material or composition of matter which forms a bond subsequent to its application to the suture or the needle with or without subsequent chemical or heat treatment.

A considerable variety of adhesives can be used for securing the suture to the needle. The suitability of any particular adhesive will depend however upon the material forming the suture, the form of recess into which the end of the suture is to be secured, and also the strength of the adhesive bond which the adhesive is capable of forming. In certain instances it is advisable to use an adhesive which is flexible so that it does not tend to cause the suture to snap at point of entry into the recess. The sutures have at sometime or other in their existence to be sterilised before use and therefore the choice of adhesive will depend in some measure on the nature of the sterilising process. For example, a particularly common method comprises heating the suture in super-heated steam or in containers surrounded by hot oil. When these methods are employed it is not desirable to use a thermoplastic substance as an adhesive since there is a considerable possibility of the suture becoming detached from the needle if there should be any relative movement between the needle and the suture- While the thermoplastic material is in a liquid or plastic state. If, however, sterilisation is carried out employing a biocidal radiation then there will usually be no objection to using a thermoplastic material as the adhesive.

Apart from possessing non-toxic properties one of the most important requirements of the adhesive is that it should be capable of forming a secure anchoragebetween the suture and the needle. The strength'of the bond is conveniently determined by a so-called pullout test which is described below. In general the required pull-out strengths will depend upon the gauge of the suture. For example a particularly common form of suture incorporates a thread having a diameter of 12 mls. in which case the pull-out strength should be at least 1 1b. Other suitable minimum pull-out strengths relating to sutures of different gauges are tabulated be- The choice of adhesive also depends upon the nature of the recess into which the suture has to be secured. In general there is no difliculty in securing the suture to a needle which is channelled or has a slot formed into it. However it is somewhat more difficult to assemble a suture and needle in which there is a narrow hole closed at one end. Thus if the end of a catgut suture which is relatively non-porous is treated with a liquid adhesive and then inserted into the narrow hole, an airaa jeas i lock tends to be formed which prevents the introduction of a sufiicient quantity of adhesive. In those cases where the suture is of a nonporous variety it is generally more convenient to treat the end of the suture with a powdered adhesive since it is found that in this way sufficient can be introduced in the hole. Powdered adhesives are gene porous materials it is convenient merely to impregnate the end of the thread with a liquid adhesive before insertionq The adhesive in such instances might comprise one that has been rendered liquid (or semi-liquid) by heat prior to insertion of the suture or one that is solid but is applied in the form of a solution or an emulsion. While it will be appreciated that a great many conven-,

tional adhesives can be used the following classes have been found to give particularly good results: Polyepoxides, polyamides, the condensation products of aldehydes with phenol, ureas, melamine, certain polyesters derived from saturated and unsaturated monomers, and the materials which are sold under the following trade- 'marks: Araldite 1, Araldite F, Araldite D, Araldite 125,

Araldite 33/900, B.T. 30d, Bondmaster M621, Bondmaster M645, Epikote Resin Nos. 815, 828, 834,- Versamid 112, either alone or mixed with Araldite D and Araldite 125, and a copolymer of n-butyl and n-hexyl methacrylate.

Having regard to the fact that nylon and catgut are the two most important materials from which sutures are made and that heating to temperatures of about 150 C. in air is the preferred methodof sterilisation it has been found that epoxi resins give best results.

Preferred methods of performing the invention will now be described by way. of example with reference to the drawings accompanying the provisional specification and wherein: I

Figure 1 illustrates one type of needle with suture inserted.

Figures 2A and 2B, show such needles having adhesive introduced into them.

Figure 3 illustrates a typical suture just before insertion into a typical needle.

.Figure 4 illustrates the preferred method of heating -a needle between electrodes to melt an adhesive inpowder form prior to insertion of the suture.

Figure 5 shows a modified form of the attachment shown in Figures 1 and 3, and,

end is swaged.

Figure 7 accompanying the present specification shows storing atmospheric pressure this air is replaced by the fluid adhesive. When subsequently, the needle is withdrawn by being pulled right through the pad away from the paper side, the excess of adhesive is wiped off by the movement of withdrawal through the felt.

Afterthe adhesive has been applied to the needle end and the suture has been inserted, as hereinbefore described the needle end is usually subjected to heat treatment although in some instances it may. be desirable to heat the needle before insertion of the suture. In its heated state the adhesive conforms to the end of the suture and sets on cooling or by curing during heating according to its composition to lock the suture to the needle.

As shown in Figure 4 the needle may be heated by the discharge of electric current through it by electrodes 15,

16. Temperatures between 50 and 130 C. are suitable.

Other methods of heating the needle are by contact with hot metal blocks, or placing it in a narrow beam of radiant heat, or by high frequency electric induction.

Any effective and controllable method of heating will do.

The adhesive forms a bond between the sides and end of the'suture and the sides and end of the hole in the needle so as to hold the suture and needle together with very great strength.

Figure 5 illustrates how, by the application. of slightly greater heat, between 110 and 140 C., the end 13 of a catgut suture may be slightly deformed toconstitute a plug 17 which fills the end of the needle and is retained there by a 'collar 18 consisting of a minimal amount of adhesivefadhering to the needle but not necessarily to the catgut. Such a collar is readily formed by heating a limited amount of adhesive powder in the end of the needle so that air expanding out of the end of the needle blows out a bubble of the melted adhesive. The catgut is then' inserted. while the adhesive is still liquid and is. pushed firmly in during further heating to denature slightly the collagen of which the catgut is composed until the suture end is fattened so as to fill the hole behind the adhesive.

Some suture materials are not responsive to this method but must necessarily be fixed by simple'adhesion. It may be of advantage to toughen the surface of the suture material by grinding or other means to increase the strength of adhesive. In the case of certain combinations of suture and needles as shown in Figured however, it may be advisable to swage or otherwise distort the needle about the suture end in addition to bonding with an adhesive, one of the objects being that the adhesive may fill certain spaces between the suture end and the needle where contact would otherwise be poor, and another, that inthe case ofcertain sutures the adhesive may penetrate the intersticesof the suture end a perspective view of a test machine to establish the strength of flint between the needle and a suture.

As shown in Figure 1 theneedle 161 is provided at its blunt ,end with a substantially axial hole 12 Within which is inserted and bonded the end 13 0f a suture.

The bonding adhesive is introduced into the hole 12 prior to the insertion of the suture end 13 and in onev methodtshowninFigure 2A) the hole 12 of'the'needle 10 is filled with adhesive powder. by pushing the needle into a quantity of powder a suitable co11tainer 20 l A preferred method for introducing adhesive in liquid form into the hole 12 is shown in Figure 2B, showing three needles being treated simultaneously. Each needle 12 is inserted into and almost through a paper-faced piece of felt 21, so that the open end of'the needle is almost flush .with'the paper surface 22-, and the liquid or paste adhesive 23 lies above the paper. On reducing the pressure in a vacuum vessel 2.4 surrounding the needles, the air entrapped in the needle ends is blown out through the layer of adhesive, and on reand render it less compressible.

As an alternative to the employment of a single adhesive, one adhesive which will adhere to the needle metal may be put into the needle end and another adhesive maybe used to coat thinly the end of the suture to be inserted, provided the two adhesives will adhere to each other when put into contact in the necessary conditions. In addition one or more supplementary intermediate adhesives may be introduced until a strong bond is established across from the suture to theneedle. Such a layered system to provide adhesion might make use of a specially low melting solder to modify the internal sur' face of the needle, and of metallisation of the end of the suture, such as by electro-deposition of metal or the application of a paint containing a metallic powder to it,

so that by the application of suitable heat, the suture of. time. With others,. such as fusible metal solder, no curing is necessary at all. As stated above in some instances the adhesive may be applied originally to the end of the suture rather than to the needle end. As shown in Figure 7 in order to test the strength of an adhesive bond between a suture 37 and a needle 38 the latter is first clamped between the jaws 32 of a vice 39 which is attached to a pivoted end 33 of a notched brass beam 34. The end of the beam opposed to the pivoted end is supported on a rest 35. A weight 36 rests in a notch on the beam which is graduated in lbs. and ozs. It is possible to vary the position of the weight 36 along the beam 34 and the elfect of placing the weight in a position nearer the free end is to increase the amount of the turning force which has to be applied at the vice in order to raise the free end of the beam from the rest.

With the needle 38 gripped between the jaws of the vice the thread 37 is pulled firmly but not jerkily in a direction opposed to but parallel to the direction of the beam until the free end of the beam 34 rises from the rest 35. The process is then repeated with increased loads until the stage is reached when the beam cannot be lifted. The strength of the adhesive bond expressed as the pull-put strength is defined as the maximum number of pounds weight which as read from theposition of the weight in the beam which can be raised without the thread being pulled out of the needle.

This invention is illustrated by the following examples:

Example 1 A polyepoxy adhesive sold under the trademark Aral- I dite 1 was partially precured and after powdering was introduced into a hole which had been drilled along the longitudinal axis of a suture needle. The head of the needle was then heated between a pair of electrodes as illustrated in Figure 4 until the adhesive was seen to have become fluid. The end of a catgut suture thread having a diameter of 14 mils. and which has previously been trimmed with a razor blade was then inserted into the hole after which the needle with attached thread was removed from the electrodes and allowed to cool.

The thread and needle were then given a slight but firm pull apart to test whether an initial bond had been formed after which the combination was placed in an air oven and heated to 110 C. for 18 hours to effect sulficient curing of the adhesive to prevent the thread from becoming detached during subsequent operations. The needle with thread attached was then heated for a further period of 8 hours at 100 C. after which it was sterilised by heating to a temperature of at least 150 C. for 1.5 hours.

The strength of the adhesive bond was tested according to the method described above and was found to be 3.5 lbs.

ExampleZ A catgut thread having a diameter of 13 mils. was inserted into a drilled and internally threaded needle the hole of which had been previously filled with a dispersion of adhesive comprising sodium silicate. The needle and thread was then heated to 100 C. for 3 hours. The pull-out strength was found to be 2.2 lbs.

Example 3 The end of a nylon thread having a diameter of 16.6 mils. was roughened and inserted into the groove of a channeled needle which previously had been filled with a thermosetting phenol/formaldehyde resin manufactured by the Cornbrook Chemical Co. The needle was cured and sterilised according to the method described in Example 1. After sterilisation the pull-out strength was found to be 3.0 lbs.

Example 4 Six needles with holes drilled into their heads were secured to a catgut thread of diameter 15 mils. by means of aurea formaldehyde thermosettingresin sold under the trademark B.T. 30d by Beetle Products Ltd. Curing of the resin was elfected by heating to C. for 2.5 hours.

Pull-out strength Needle:

- Lbs. 1 2.50 2 4.00 3 3.00 4 4.00 5 2.00 6 3.75

Example 5 Example 6 Pull-out strengths of above 2.5 lbs. were obtained when black braided silk threads were secured to drilled needles using epoxy thermosetting adhesive sold under the trademarks Araldite M 621 and Araldite M 645. After application of the adhesive and insertion. of the threads the sutures were heated for the same curing times I as employed in Example 1 in order to harden the resins.

Obviously any type of needle may be employed when the method according to the invention is used for attachment as distinct from earlier methods of attachment which require particular needles for use with particular methods of needle attachment. Moreover, with the present invention the needle is generally re-usable if an error has been made in the attachment while prior methods being entirely mechanical and involving a distortion of the metal of the needle once attachment has been done do not permit a needle to be re-used in case of an error in manufacture and thus result not only in waste of operators time but also in waste of materials.

7 Although the foregoing description relates specifically to surgical sutures and surgical needles it is to be understood that the invention is not limited thereto and may be employed in the attachment of needles to filaments or thread-like materials which are not necessarily used in surgery. Accordingly in the appended claims, unless otherwise stated, the terms needle and sutures" are to be understood to include needles and filaments or thread-like materials generally as well as those specifically prepared or adapted for surgical use.

What we claim is:

1. Method of attaching a suture to a metal needle which comprises inserting the end of the suture together with a heat activatable adhesive material having'a bonding affinity for both the metal of the needle and the suture, within a recessed portion of the needle and subsequently heat treating the needle and the suture end to activate and set the adhesive.

2. Method of attaching a suture to a metal needle which comprises inserting the end of the suture and a quantity of an epoxy resin having a bonding affinity for both the metal of the needle and the suture in a recessed portion of the needle and heating the needle and the suture end to set the resin.

3. Method of attaching a suture to a needle which comprises deforming an end of the suture to constitute a plug, inserting the said end in the suture in the recessed portion of the needle together with a heat activatable adhesive whereby the adhesive forms a collar surrounding the suture and within the needle in rear of the plug, and heat treating the needle and the suture 'end to activate and set the adhesive.

7 7 r 4. Method of attaching a suture to a :metal needle which comprises formingt'an axial recess in the needle at the end thereto remote from the needle point, inserting an end of the suture within said recessed portion of the needletogether with a thermoplastic adhesive having a bonding aflinity for both the metal of the needle and the suture, heating Lheneedle and the suture .endto melt the adhesive,.and, thencooling thetneedleand the suture end to set the adhesive. 1

5.7 A metal surgical needle and a suture attached thereto, an end of thesuture being housed within a recessed portion in the needle and secured thereto by antepoxy resin having a bonding affinity for both the metal of the needle and the suture. I I

6.' A metal needle havinga suture attached thereto, said needle being provided with an axially aligned recess at the end thereof remote from its point and housing an 'end of the suture, the suture being secured Within said recess by an adhesive having a bonding affinity for both the metal of the needle and the suture 7. A metal surgical needle having a catgut suture attached thereto, said needle being provided. with an axially aligned recess at the end thereof remote from its point and housing an end of the suture, the suture being secured within said recess by an epoxy resin adhesive having a bonding afl'inity for both the metal of suture.

8. A metal surgical needle anda suture attached thereto,.an end of said'suture being housed within a recessed end portion of said needle remote from its point and secured by an adhesive having a bonding affinity for boththe metal of the needle and the suture, said adhesive .being selected from the groupconsisting of polyepoxides, polyamides, the condensation products of aldehydes with phenol, urea, melamine, and adhesive polyesters derived from saturated and unsaturated monomers.

References Citedin the file of this patent UNITED STATES PATENTS the needle and the OTHER REFERENCES Dunnz Typical Applications of Epoxy Resins, The Rubber and Plastics Age, vol. 35, February 1954, pages .84-87. (Copy in Division 60.) 

